Solve the given problem ":

Dear student,
since b = 4 N v = 4 N $\frac{4}{3} \mathrm{\pi } {\mathrm{r}}^3$
4 $\mathrm{\pi }$ x 10^-4  =  4 x 6 x 10²³ x $\frac{4}{3} \mathrm{\pi } {( \mathrm{z} \times 10-9 )}^3$
            10^-4 =  4 x 6 x 10²³  x z³ x 10^-27 /  3 
             z ³ =  1/ 8 
            z  = 1/2 or 0,5 
Regards